Ready-To-Eat (“R-T-E”) breakfast cereal have long been fortified with various vitamins and minerals including calcium. For example, U.S. Pat. No. 2,166,797 (“Process of Fortifying Cereals Products with Minerals” issued Jul. 18, 1939) teaches a 50:50 mixture of sodium phosphate with calcium carbonate to provide about 0.1% calcium). Health and nutrition interests have recently focused upon increasing the calcium content of foods and in R-T-E cereals in particular. The present invention provides improvements in the mineral fortification of cooked cereal products such as puffed R-T-E cereals and fried snacks. In particular, the present invention provides improvements in providing puffed R-T-E cereals with high levels of calcium.
For adults, recent medical studies have indicated that a diet containing the U.S. recommended daily allowance (RDA) of calcium might be effective in preventing or mitigating osteoporosis, and also possibly high blood pressure and colon cancer. Calcium is also of particular nutritional value in growing children to support bone growth. There is therefore great public interest in the preparation and consumption of food products that will supply the recommended daily allowance of calcium.
In view of the desire for introducing more calcium into diets, especially children's diets, it would be desirable if such R-T-E cereal products were fortified with supplemental calcium to provide high levels of calcium. The current recommended daily allowance for adults is 1000 mg of Ca. By “high levels” as used herein is meant a product that provides at least 20% of the recommended daily allowance of calcium (200 mg Ca) in a single serving of food product. By current food labeling regulations, such products can be characterized as an “excellent” source of calcium as compared to those products that supply only 10% or 100 mg calcium which can only be described as a “good” source of calcium. For R-T-E cereals “high levels” means having at least 0.65% elemental calcium (dry weight) or about 200 mg calcium per serving (typically about 30 g of product) of R-T-E cereal.
Calcium can be added in limited amounts to R-T-E cereal products. However, at higher levels of calcium fortification, the presence of such high amounts of calcium ingredients can adversely interfere with other desired characteristics. For example, high levels of added calcium ingredients can negatively affect the taste, texture, color or density of the R-T-E cereal products.
One approach is to providing higher levels of calcium fortification is to employ calcium carbonate as the calcium ingredient. Calcium carbonate is preferred in large part since its calcium level is quite high (about 40%). Also, calcium carbonate is insoluble and relatively inert in conventional cereal processing operations. Moreover, CaCO2 is an inexpensive sources of calcium.
Among the various types of R-T-E cereal products, puffed R-T-E cereals are especially popular with children. Thus, it would be desirable to provide puffed R-T-E cereal with high levels of calcium fortification. Calcium carbonate has been used to provide calcium fortification to R-T-E cereals but at lower levels (i.e. under 0.5% calcium). However, puffed R-T-E cereals are especially difficult to fortify with high levels of calcium incorporated into the cooked cereal dough. For example, when CaCO2 is used to provide the calcium, the calcium ingredient acts as a leavening agent and can cause over leavening of the puffed pieces even when conventional leavening ingredients are not added. Both product appearance and texture can be adversely affected. Counterintuitively, over leavening can actually result in under expansion. One technique involves applying a topical coating especially a sugar coating to provide the desired level of calcium fortification (see, for example, co-pending commonly assigned U.S. Ser. No. 09/503,953, entitled “Presweetened Ready to Eat Cereals Fortified with Calcium and Methods of Preparation”, filed Feb. 14, 2000 and incorporated herein by reference). While useful to provide calcium fortification for those puffed R-T-E cereals intended to be presweetened, not all puffed R-T-E cereals are presweetened.
Extruders are often used in the preparation of various food products and especially in the preparation of ready-to-eat (“R-T-E”) cereals such as puffed products. Extruders, especially cooker extruders, are desirable because a single machine can produce large quantities of a cooked cereal dough in a short period of time. Such cooker extruders can be used to prepare cooked dough extrudates which can thereafter be formed into individual cereal or snack pieces, with the formation of such pieces possibly involving puffing the pieces to form finished puffed R-T-E cereals. In another variation that is increasingly popular, the conditions of the extruder and the cooked cereal dough are such that the dough puffs immediately upon being extruded and is cut into individual puffed pieces at the die head. Such a process is referred to generally as “direct expansion”. However, the problems in controlling expansion of cooked cereal doughs by direct expansion are even more severe when calcium carbonate is added to the cooked cereal dough at levels sufficient to provide high levels of calcium.
Still another problem is that such puffed R-T-E cereal products are often fabricated from lightly colored cereals such as rice and/or corn since such lightly colored and flavored cereal materials are popular with children due to the absence of a strong grain flavor. However, for lightly colored cereals such as than that are rice and/or corn (maize) based, calcium fortification can result in development of off-colors especially when CaCO2 is used to provide the calcium.
In view of the current interest in providing R-T-E cereals having high levels of calcium fortification, it would thus be desirable to provide puffed R-T-E cereal products fabricated from cooked cereal doughs formulated to comprise high levels of calcium. Surprisingly, the multiple problems of incorporating high levels of calcium can be overcome. The present invention resides in important part in the selection of insoluble calcium phosphate salts of particular particle size level for incorporation at high levels in cooked cereal doughs. More surprisingly, by selecting these particular materials, puffed R-T-E cereals can be prepared by direct expansion from twin screw extruders.
Still another advantage is that such high levels of calcium fortification can be provided in puffed R-T-E cereals prepared by direct expansion using twin screw extruders of cooked cereal doughs comprising lightly colored and flavored cereals such as corn and rice without discoloration.
These and other advantages and benefits are taught and described in the following specification.